On Tue, 2006-05-16 at 13:25 -0700, Jonathan Hughes wrote: > I am trying to apply nmds to a data matrix but I receive the > following error message: > > Error in isoMDS(dis, y = y, k = k, maxit = maxit) : > zero or negative distance between objects 5 and 7 > > The data are in a vegetation cover-class matrix (species in columns, > plots in rows, classes 1-8 with lots of zero values) converted to a > dissimilarity matrix (bray curtis). > > I assumed that objects 5 and 7 refer to rows of my original data; and > they do have the same species with the same cover classes. I deleted > one of these rows but I received the same error message with a rerun > of nmds. As it turns out, the new rows 5 and 7 are the same. How do > I avoid this problem?
Jonathan, this is a FAQ in the proper sense of the word: this is frequently asked. Last thread was on April, 2006. See https://stat.ethz.ch/pipermail/r-help/2006-April/092598.html and answers. You may also use RSiteSearch with keyword "isoMDS" to find other (and older) threads. cheers, jari oksanen -- Jari Oksanen -- Dept Biology, Univ Oulu, 90014 Oulu, Finland email [EMAIL PROTECTED], homepage http://cc.oulu.fi/~jarioksa/ ______________________________________________ R-help@stat.math.ethz.ch mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html
